The decision was influenced by the failure of Fernando Alonso to qualify for this year's Indianapolis 500.
Dengan melengkapkan perlumbaan 60 pusingan di litar sepanjang 5.4 kilometer Hetar pecah rekod dalam aski pertamanya
Jordan King will drive for the Rahal Letterman Lanigan team in next year's Indianapolis 500.
However, McLaren are still considering competing at the Indianapolis 500.
Scott Dixon added to IndyCar Series titles won in 2003, 2008, 2013, and 2015 by finishing second at the Grand Prix of Sonoma.
James Hinchcliffe finished ahead of Josef Newgarden to win the Iowa Corn 300.
Josef Newgarden won the 10th IndyCar race of his career, finishing ahead of Ryan Hunter-Reay.
A ferocious downpour forced the postponement of the IndyCar Grand Prix of Alabama.